There are some networks of SQM photometers that provide measures of the night sky brightness every night. The analysis of the data provided by the photometers allows the researchers to monitor the nightly, monthly and yearly evolution of the NSB and the relationship with light sources of pollution in intensity and distance. The photometers that are measuring in protected areas will alarm the researchers about eventual increasing of light pollution that could affect the environment.

Using models of light dispersion on the atmosphere one can determine which light pollution sources are increasing the sky brightness at different places and in which extension. Networks of fixed photometers acquiring data every night are one of the main inputs to test these models. The collaborative effort of many people provides the necessary data to derive scientific results.

We present the SQM network of the Spanish Light Pollution Research collaboration http://guaix.fis.ucm.es/splpr/SQM-REECL that is growing with the help of amateur astronomers and interested citizens. Data are being archived in the Spanish Virtual Observatory (SVO) using the IAU and IDA community standard data format for light pollution measurements.